The most efficient apparatus for inputting alphanumeric information into a computer is a keyboard. Because many computer devices are miniaturized or in an attempt to lower the cost of manufacturing a small computer or because of some concept of elegance, many of these devices have an alternative to a full size keyboard. For example a virtual keyboard may be made to appear on a touch screen, which is simply too small for conventional typing. People have managed to adapt by learning to type with two thumbs or software controllers handle the inaccuracy of typing on miniature keyboards by guessing what the user intended to type. Also, component manufacturers have produced auxiliary full size keyboards that can plug into small computers, or even full size computers, through a USB or serial port or docking station.
There have been attempts to provide systems that detect the motion of a typists fingers as an alternative to having a series of contact switches that feed signals to the computer. Some have employed light scanners to form a real-time image of the position of the user's fingers and relied upon an acoustic signal to detect that the hand has tapped a surface. Others have used rows of acoustic sensors to replace rows of keys on a typewriter input and made the device more accurate by determining from analysis of the acoustic waveform which finger has struck a surface. Others provide a reduced set of keys and use a series of sound sensors together with optical sensors to identify which finger has struck the reduced keyboard.
While each of the prior art devices purports to be able to determine the location of a user's fingers striking a surface, each is a complex combination of multiple sensors which does not solve the problem of providing a simple setup for virtualizing keyboard input.